水晶体再建術後の眼内レンズ光学部の傾斜方向と程度を観察する新しい方法

A new method to observe the direction and magnitude of tilt of intraocular lens optics after cataract surgery

要約　目的：前眼部光干渉断層計を使用し，同例の水晶体再建術直後，および術1年後の2時期で撮影後，それぞれの角膜形状と隅角底の位置を一致させて合成画像を作成し，両時期における眼内レンズ（IOL）の傾斜方向と程度を新しい方法で観察する。

対象と方法：1ピースIOL（SZ-1，NIDEK社）挿入例の1眼と，3ピースIOL（AN6K，KOWA社）挿入例の1眼を代表例とし，両例とも水晶体再建術直後および術1年後に撮影された画像を合成した。次に合成画像上の左右の隅角底を結ぶ直線①と，左右光学部のエッジ中央部を結ぶ直線を術直後，1年後で作成して各々直線②，③とし，直線①と直線②，③の成す角度から傾斜方向を決定した。術直後，1年後ともに光学部中心点を通る位置まで直線①を下方に平行移動させ，画像上の光学部右側エッジ中央部から平行移動した直線①までの垂線の長さを計測し傾斜程度とした。画像解析はadobe社製のphtoshop，illustrator，計測プラグインソフトBPT-Pro4を使用した。

結果：SZ-1挿入例で術直後が12時〜2時〜4時，1年後では9時〜12時〜2時，AN6K挿入例で術直後が12時〜2時〜4時，1年後では10時〜2時〜3時，ともに硝子体側へ傾斜していた。また傾斜程度は，SZ-1挿入例の術直後で2，3時，1年後で10時，AN6K挿入例の術直後で3時，1年後で2時の傾斜がともに大きかった。

結論：本手法は，挿入後の位置変化や傾斜が少ないIOLを開発する際に有用な情報を与えるものと考えた。

Abstract　Objective：To observe the direction and magnitude of tilt of an intraocular lens（IOL）implant on composite images of anterior segment optical coherence tomography immediately and 1 year after cataract surgery and to align these images for each subject using their corneal morphology and the position of the angle recess.

Subject and Methods：A person with a single-piece IOL（SZ-1, Nidek Co., Ltd.）and a person with a three-piece IOL（AN6K, Kowa Company, Ltd.）were studied as representative examples. For both patients, images were acquired at same positions in two terms previously described and those acquired from two terms were composited. Subsequently, the straight line connecting the left and right sides of the angle recess on the composite image was labeled Line ①, and the straight lines connecting the centers of the left and right edges of the optical element in two terms were labeled Lines ② and ③, respectively. The angles formed by Lines ①, ②, and ③ were used to measure the direction of IOL tilt. Additionally, Line ① was extended until it passed through the center of the optical element on the image acquired from two terms, and the length of the perpendicular line drawn from the center of the right edge of the optical element to the extended Line ① was measured. The lengths of these two lines were used to calculate the magnitude of tilt. Images were analyzed using Adobe photoshop, illustrator and the plug-in BPT-Pro4.

Results：For SZ-1 IOL, a tilt towards the vitreous body was observed from the 12-2-4 o'clock immediately after surgery and from the 9-12-2 o'clock 1 year after surgery. For AN6K IOL, a tilt towards the vitreous body was observed from the 12-2-4 o'clock immediately after surgery and from the 10-2-3 o'clock 1 year after surgery. For SZ-1 IOL, the tilt towards the vitreous body was the greatest in the 2 and 3 o'clock immediately after surgery and in the 10 o'clock 1 year after surgery. For AN6K IOL, the tilt towards the vitreous body was the greatest in the 3 o'clock immediately after surgery and in the 2 o'clock 1 year after surgery.

Conclusion：This novel observational method will prove useful in the development of IOLs capable of minimal change in position and tilt after insertion.